/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.phoenix.expression.function;

import java.sql.SQLException;
import java.util.List;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.phoenix.compile.StatementContext;
import org.apache.phoenix.expression.CurrentDateTimeFunction;
import org.apache.phoenix.expression.Expression;
import org.apache.phoenix.parse.CurrentTimeParseNode;
import org.apache.phoenix.parse.FunctionParseNode.BuiltInFunction;
import org.apache.phoenix.schema.tuple.Tuple;
import org.apache.phoenix.schema.types.PDataType;
import org.apache.phoenix.schema.types.PTime;
import org.apache.phoenix.util.EnvironmentEdgeManager;

/**
 * Function that returns the current date accurate to the millisecond. Note that this function is
 * never evaluated on the server-side, instead the server side date is retrieved (piggy-backed on
 * the call to check that the metadata is up-to-date) and passed into this function at create time.
 * @since 0.1
 */
@BuiltInFunction(name = CurrentTimeFunction.NAME, nodeClass = CurrentTimeParseNode.class, args = {})
public class CurrentTimeFunction extends CurrentDateTimeFunction {
  public static final String NAME = "CURRENT_TIME";
  private final ImmutableBytesWritable currentDate =
    new ImmutableBytesWritable(new byte[PTime.INSTANCE.getByteSize()]);

  public CurrentTimeFunction() {
    this(EnvironmentEdgeManager.currentTimeMillis());
  }

  public CurrentTimeFunction(List<Expression> children, StatementContext context)
    throws SQLException {
    this(context.getCurrentTimeWithDisplacement());
  }

  public CurrentTimeFunction(long timeStamp) {
    getDataType().getCodec().encodeLong(timeStamp, currentDate);
  }

  @Override
  public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
    ptr.set(currentDate.get(), 0, PTime.INSTANCE.getByteSize());
    return true;
  }

  @Override
  public final PDataType getDataType() {
    return PTime.INSTANCE;
  }

  @Override
  public String getName() {
    return NAME;
  }
}
